L.7.2.2 Embedded Objects

For all other embeddings, the embedded object is stored in an arbitrary format defined by the application whose data is being embedded. These generic embedded objects must be the target of the Embedded Object relationship: http://purl.oclc.org/ooxml/officeDocument/relationships/oleObject. When parsing the data stored in an embedded object part, an application must use the associated ProgID (whose location is described in the following subclauses) for the object.